Lamp



Oct. 18, 1955 w. G. GRIMES LAMP Filed March 19, 1953 mans INVENTOR Warren G- Grzlznas ATTORNE Y United States Patent Office 2,721,289 Patented Oct. 18, 1955 LAll [P Warren G. Grimes, Urbana, Ohio Application March 19, 1953, Serial No. 343,319

8 Claims. (Cl. 313-114) This invention relates to a lamp and has for an object to provide an improved lamp which will give a much greater intensity of light in the desired directions.

A further object of this invention is to provide a vehicle position or airplane running light lamp that provides a great deal more light than and is an improvement over applicants previous lamp as shown in Patent No. 2,237,072 and over all other lamps for this same general purpose.

A further object of this invention is to provide a prefocussed lamp of any suitable size which will direct a maximum of light flux in the desired directions, which may be made in any type of single or double contact indexing base of any base size.

A further object of this invention is to provide an improved lamp which produces a very high light flux density in a forward and a near forward direction.

A further object of this invention is to provide an improved lamp that may be used in many locations, such as a running light, tail light, position light, fuselage light or elsewhere in an airplane or other aircraft, in land or water vehicles, for general lighting as well as a clearance light or a rotating signal light or in any location where a good, effective light beam is required from a small unit.

Briefly, this invention includes a lamp bulb mounted in a suitable lamp base, the major and forward portion of the lamp bulb being transparent and spherical, the rearward portion including a lower or basal portion which is ellipsoidal in shape and merges with an upper portion which is hyperboidal in shape, the hyperboidal also including the paraboloidal since in the mathematics of conic sections the hyperbola becomes a parabola when the eccentricity decreases to unity. The bulb is secured on a base, usually cylindrical, and the base supports a light filament which is located rearward of and below the radius center of the spherical section. The lamp base is to be mounted in a socket in the vehicle aircraft or other location in such a position that the axis of the base is preferably but not necessarily tipped rearwardly approximately 12.5 and the socket mounting may. extend up to a plane extending through the light filament and the boundary between the upper and basal rearward sections and parallel to the flight or travel axis in the case of a vehicle. Both rearward sections are'provided with a reflecting surface extending to a boundary determined by a plane through the lamp filament parallel to the base axis and extending through thespherical section just forward of its merging boundary with the rearward sections.

With the foregoing and other objects in view, this invention comprises the combination, construction and arrangement of parts hereinafter set forth, claimed and disclosed in the accompanying drawings, wherein: V

Fig. -1 is a perspective view of a lamp of this invention before the reflective material has been applied.

Fig. 2 is a top plan view of the lamp of this invention mounted in a socket mounting means in the right wing of an airplane.

Fig. 3 is a view of the lamp bulb sectioned on line 33 of Fig. 4.

Fig. 4 is a front side view of Fig. 2.

There is shown at 10 thelamp of this invention, and includes a lamp base 11, which, although shown as being of the type having a single contact 12 and bayonet joint cooperating fingers 13 and 14 for mounting it in the socket mounting means shown generally at 15, may be of any conventional single or double contact type of any conventional standard, medium or mogul size. As will hereinafter be shown, the socket 15 is so mounted in the aircraft, vehicle or other location that its axis is preferably tipped horizontally rearward approximately 12.5 to the flight or direction axis of the aircraft or other vehicle.

Supported on the lamp base 11 is the lamp bulb 16. The lamp bulb 16 consists of a spherical section 17 which is transparent, and hence, extends on the side in which it is desired to direct the light, and is hence hereinafter referred to as the forward side. This spherical section 17 provides slightly more than one half the bulb 16, as shown. Merging with the spherical section 17 is the rearward lower or basal section 18 which is ellipsoidal in shape, and merging with the upper boundary 20 of this ellipsoidal section 18 and the rear boundary 21 of the spherical section 17 is the rearward upper section 22 which is hyperboloidal in shape, but also may be paraboloidal, such being one specific form of the hyperboloidal.

Supported by the base 11 in the usual manner are the filament lead posts 23 which support the filament 24 therebetween. It will be particularly noted that the filament 24 is not located at the radius center 19 of the spherical section 17, but instead is located behind or below and rearwardly of such center point 19, as shown. A silver reflector 25 is provided over the rearward sections 18 and 22 of the lamp bulb 16, the edge or boundary 26 of the reflector 25 being located on the spherical section 17 adjacent its rear boundary 21 in a plane extending parallel to the axis of the base 11 and through the filament 24. At the bottom, a non-silvered neck 28 is left just above the lamp base 11, as shown.

The location of the filament 24 rearward of and below the radius center 19 of the spherical section 16 is provided to comprise for several factors in good lamp design:

a. A shorter focal length is obtained (filament to reflector surface).

b. The bulb shape is improved for good manufacture and basing.

c. The maximum reflecting surface is made possible.

a. The conjugate focus F is not too close to the bulb.

The bulb 16 is also preferably tipped rearward approximately 12.5 of the base axis as a part of this compromise.

As set forth above, the lamp may be made in various sizes and various size and type bases, but on Fig. 3 of the drawing, certain measurements are illustrated as applying to one particular size of bulb 16 and as illustrating the preferred proportions. The particular size illustrated, as an example only, is where the radius of the spherical section 17 is inch. In such case, the filament 24 is located Ms inch below the spherical radius center 19 and rearwardly thereof inch as shown. The filament 24 is thus shown as being inch forward of theboundary 20 between the rearward basal section 18 and upper section 22. A suitable size base 11 for this lamp 16 would be .675 inch.

The lamp socket 15 is shown as being tipped rearwardly of the flight axis approximately 125 as shown, and may be provided with a socket bowl 27 which extends at most to a plane through the filament 24 parallel to the flight or direction axis as shown, the reflector boundary 26 forming an angle of with the flight axis.

The crux of the invention is in the rearward basal ellipsoidal shape 18 and upper hyperboloidal or paraboloidal shape 22, with the reflector located thereon as shown to produce in the forward and near forward as required by both safety and C. A. A. regulations when used on an aircraft position running on tail lights, a very high light flux density. The legal regulations require that the light be provided 90 above and below the source and from dead ahead to 110 to each side of dead ahead, and the reflector surface 25 meets these requirements.

This light flux leaves the bulb 16 above the plane through the filament 24 (which is parallel to the flight axis and also extends through the boundary 2% between the basal and upper rearward shapes). The angular extent throughout which the reflecting surface 25 redirects and converges the backwardly emitted light from the filament 24 into the forward direction depends entirely on the parameters'29 and of the ellipsoidal surface 18 and the hyperboloidal or paraboloidal surface 22.

When used as a running light, a single lamp is located in the forward outer edge of each wing tip, covered with a red glass in the left wing tip and a' green glass in the right wing tip as customary. The axis of each lamp is horizontal, and the light is emitted from straight ahead to 110 to the side, and also above and below the horizontal through 180.

Summarizing, the ellipsoidal reflecting surface 18 redirects light initially emitted from the filament 24 to the rear and towards the lamp base 11 within an appreciable solid angle such that it is converged into a much smaller solid angle and leaves the lamp bulb 16 forward and away from the lamp base 11. The hyperboloidal (or paraboloidal) reflecting surface 22 redirects light initially emitted from the filament 24 to the rear and away from the lamp base 11 Within an appreciable solid angle such that it is converged into a much smaller solid angle and leaves the lamp bulb 16 forward and away from the lamp base. Thus, both surfaces 18 and 22 produce a relatively high light flux density or candle power in the desired direction and do this even though the lamp base 11 and bulb 16 up to the filament plane are recessed into the socket bowl 27.

While the device has been shown and the structure described in detail, it is obvious that this invention is not to be considered as being limited to the exact form disclosed, and that changes in detail and construction may be made therein within the scope of what is claimed, without departing from the spirit of this invention.

Having thus set forth and disclosed thenature of this invention, what is claimed is:

1. In a lamp, a lamp base, a light filament, and a lamp bulb extending from and above said base, said lamp bulb consisting of a forward spherical section, an upper rearward hyperboloidal section, said light filament being located slightly rearwardly of and below the radius center of said spherical section, and a basal rearward ellipsoidal section.

2. A lamp comprising a lamp base, a light filament, and a lamp bulb extending from and above said base, said lamp bulb consisting of a forward spherical section, an upper rearward hyperboloidal section, said light filament being located slightly rearwardly of and below the radius center of said spherical section, and a basal rearward ellipsoidal section, and a reflecting surface covering both said rearward sections.

3. A lamp comprising a lamp base, a light filament, and a lamp bulb extending from and above said base, said lamp bulb consisting of a forward spherical section, an upper rearward hyperboloidal section, said light filament being located slightly rearwardly of and below the radius center of said spherical section, and a basal rear- 4 ward ellipsoidal section, and a reflecting surface covering both said rearward sections, the major portion of said spherical section being transparent, said rearward reflecting surfaces redirecting a high light flux through the transparent forward spherical section above a basal portion thereof.

4. In a lamp, a lamp base, a light filament, and a lamp bulb extending from and above said base, said lamp bulb consisting of a forward spherical section having its major area transparent, said light filament being located slightly rearwardly of and below the radius center of said spherical section, a basal rearward ellipsoidal section and an upper rearward hyperboloidal section, said light filament being located slightly rearwardly of and below the radius center of said spherical section.

5. A lamp comprising a lamp base, a light filament, and a lamp bulb extending from and above said base, said lamp bulb consisting of a forward spherical section having its major area transparent, a basal rearward ellipsoidal section and an upper rearward hyperboloidal section, said light filament being located slightly rearwardly of and below the radius center of said spherical section, and a reflecting surface covering both said rearward surfaces.

6. A lamp comprising a lamp base, a light filament, and a lamp bulb extending from and above said base, said lamp bulb consisting of a forward spherical section having its major area transparent, a basal rearward ellipsoidal section and an upper rearward hyperboloidal section, said light filament being located slightly rearwardly of and below the radius center of said spherical section, and a reflecting surface covering both said rearward surfaces and extending to a boundary determined by a plane extending through said light filament parallel to the axis of said lamp base.

7. A lamp comprising a lamp base, a light filament, and a lamp bulb extending from and above said base, said lamp bulb consisting of a forward spherical section having its major area transparent, a basal rearward ellipsoidal section and an upper rearward hyperboloidal section, said light filament being located slightly rearwardly of and below the radius center of said spherical section, and a reflecting surface covering both said rearward surfaces and extending to a boundary determined by a plane extending through said light filament parallel to the axis of said lamp base, said forward spherical section merging with said rearward sections slightly to the rear of said reflecting surface boundary in a boundary equidistant from said reflecting boundary.

8. A lamp comprising a lamp base, a light filament, and a lamp bulb extending from and above said base, said lamp bulb consisting of a forward spherical section having its major area transparent, a basal rearward ellipsoidal section and an upper rearward paraboloidal section, said light filament being located slightly rearwardly of and below the radius center of said spherical section, and a reflecting surface covering both said rearward surfaces and extending to a boundary determined by a plane extending through said light filament parallel to the axis of said lamp base, said forward spherical section merging with said rearward sections slightly to the rear of said reflecting surface boundary in a boundary equidistant from said reflecting boundary, the boundary between said upper and basal rearward sections being in a plane extending approximately through said light filament.

References Cited in the file of this patent UNITED STATES PATENTS 

